This book examines the interaction of expatriate talent with institutions in expatriates’ countries of origin in an attempt to make the potential of diasporas and their knowledge a reality. A central theme is the critical importance of these home country institutions that are interested in and capable of implementing joint projects with entrepreneurial networks of diaspora professionals. The quality of these institutions varies widely: some are extremely capable; others are not. Diaspora networks link better-performing segments of home country institutions with forward-looking segments of the diaspora. The latter have the potential to generate a virtuous cycle that develops both home country institutions and diaspora networks. The question of how to trigger and sustain such a virtuous cycle that generates benefits for all parties involved—sending countries, receiving countries, and expatriates themselves—is a central concern of this book. The focus is on the “how to” details of how to design effective diaspora networks and transform brain drain into brain gain. Most of the chapters are written by individuals with direct knowledge of diaspora interventions or with diaspora experience.